Ok, as reviews are stored as post_type in wp_posts table they are easily accessible under single-mr_review.php theme file.
With permalinks based on names (slugs), instead of $_GET parameter there’s a possibility to capture the proper review with
$slug = the_slug(); $where = “post_title=’$slug'”;
$query = “SELECT * FROM wp_posts WHERE post_type=’mr_review’ AND $where AND post_status=’publish’ LIMIT 1”;
more about on my blog https://www.potomek.eu/?go=content/blog (only polish version is currently avaiable).